A conventional method for manufacturing stack chips is described in German Patent Application No. 44 17 164, where wafers with planar high-voltage break-over diodes having an electrically conductive bonding layer in the form of a conductive adhesive on their top side are stacked directly one on top of the other. The adhesive is a prebakable adhesive allowing the individual wafers to be adjusted during stacking. After stacking, the adhesive may harden, so that the chips are electrically connected. The wafer stack is then perpendicularly cut into chip stacks. High-voltage break-over diodes that are bonded over their entire surface and are therefore mechanically strong are obtained. A disadvantage of this process is that it is relatively complex and therefore cost-intensive.
Furthermore, a manufacturing process for high-voltage diodes is known, where diffused silicon wafers are soldered together and then sawed apart into chip stacks. This process, however, is not well suited for all types of chips. For example, such a process is unsuitable for break-over diode planar chips.